Inline-level elements begin on a new line.

Inline-level elements do not begin on a new line in the document flow; instead, they flow within the content of block-level elements, allowing them to sit side by side with other inline elements. This characteristic is fundamental to how inline elements are displayed.

Examples of inline-level elements include <span>, <a>, <img>, and <strong>. Because they occupy only as much width as necessary for their content, inline elements can be placed within block elements like <div> or <p> without interrupting the flow of text. This allows for a more versatile layout, as inline elements can be interspersed with text, making them ideal for styling parts of a text or modifying links without disrupting the overall structure of a block of content.

The options related to CSS and browser behavior do not apply to the definition of inline elements as per HTML specifications. The essence of inline elements is their behavior in terms of line breaking and flow in the document, which is consistent across all compliant browsers.